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MISCELLANEA ON
ENCEPHALOPATHIES –
A SECOND LOOK
Edited by Radu Tanasescu
MISCELLANEA ON
ENCEPHALOPATHIES –
A SECOND LOOK
Edited by Radu Tanasescu
Miscellanea on Encephalopathies – A Second Look
Edited by Radu Tanasescu
Published by InTech
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Copyright © 2012 InTech
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First published April, 2012
Printed in Croatia
A free online edition of this book is available at www.intechopen.com
Additional hard copies can be obtained from orders@intechopen.com
Miscellanea on Encephalopathies – A Second Look, Edited by Radu Tanasescu
p. cm.
ISBN 978-953-51-0558-9
Contents
Chapter 1 Minimal Hepatic Encephalopathy (MHE) 1
Daniela Benedeto-Stojanov and Dragan Stojanov
Chapter 2 Uremic Encephalopathy 23
Annemie Van Dijck, Wendy Van Daele and Peter Paul De Deyn
Chapter 3 Drug-Induced Encephalopathy 39
Niels Hansen
Chapter 4 Sonographic Changes
in Hypoxic-Ischaemic Encephalopathy 61
Pilvi Ilves
Chapter 5 Neoplasm Related Encephalopathies 91
Lore Lapeire, Anne Sieben, Patrick Santens and Simon Van Belle
Chapter 6 Hepatic Encephalopathy 121
Jeffrey E. Juneau and Brendan M. McGuire
Chapter 7 Hypoxic Encephalopathy 149
Mireia Moragas Garrido and Jordi Gascón Bayarri
Chapter 8 Encephalopathy Associated
with Psychotropic Drug Therapy 167
Yuji Odagaki
Chapter 9 The Use of Microdialysis
in the Study of Encephalopathies 199
Liliana Carmona-Aparicio, Liliana Rivera-Espinosa
and Hugo Juárez-Olguín
Chapter 10 Portal-Systemic Encephalopathy in Emergency Treatment
of Cirrhosis and Bleeding Esophageal Varices 225
Marshall J. Orloff
VI Contents
Chapter 11 Future Perspectives for the Treatment
of Neonatal Hypoxic-Ischemic Encephalopathy 243
Pedro M. Pimentel-Coelho, Marcelo F. Santiago
and Rosalia Mendez-Otero
Chapter 12 Molecular Defects of Vitamin B
6
Metabolism
Associated with Neonatal Epileptic Encephalopathy 267
Mohini S. Ghatge, Martino L. Di Salvo,
Roberto Contestabile,
Dorothy N. Eseonu,
Sayali Karve, Verne Schirch and Martin K. Safo
Chapter 13 Disaccharides in the Treatment
of Hepatic Encephalopathy in Patients with Cirrhosis 291
Praveen Sharma
Chapter 14 Dopaminergic Dysfunction
in Experimental Hepatic Encephalopathy 309
Isabel Suárez, Guillermo Bodega and Benjamín Fernández
Chapter 15 Wernicke’s Encephalopathy 327
Radu Tanasescu, Laura Dumitrescu, Carmen Dragos, Dimela Luca,
Alexandra Oprisan, Catalina Coclitu, Oana Simionescu,
Lorena Cojocaru, Marius Stan, Andreea Carasca, Andreea Gitman,
Adela Chiru
and Marina Ticmeanu
Chapter 16 L-carnitine in Hyperammonemia
and Hepatic Encephalopathy 365
Jane Missler and Claudia Zwingmann
1
Minimal Hepatic Encephalopathy (MHE)
Daniela Benedeto-Stojanov and Dragan Stojanov
Faculty of Medicine, University of Nis
Serbia
1. Introduction
Hepatic encephalopathy (HE) reflects a spectrum of neuropsychiatric abnormalities seen in
patients with liver dysfunction after exclusion of other known brain disease.
Classification of hepatic encephalopathy is based on the clinical setting in which symptoms
occur (Table 1).
1
The encephalopathy of acute liver failure shares clinical characteristics with
that of cirrhosis, but also exhibits unique features. In cirrhosis, three major syndromes can
be present:
1. Episodic (precipitant-induced) encephalopathy, commonly seen in the hospital setting,
where a superimposed event is a key factor.
2. Persistent (chronic) encephalopathy, seen with extensive portal–systemic shunts and
after portocaval shunt surgery or placement of transjugular intrahepatic portosystemic
shunt (TIPS).
3. Minimal (subclinical) encephalopathy reflects alterations in cognitive function in
patients who clinically exhibit a normal mental state.
Hepatic
failure
Extrahepatic
portal-systemic
shunting
Special features
Acute liver failure
Maximal Absent Development of brain oedema and
intracranial hypertension
Cirrhosis Low-grade cerebral oedema without
overt signs of intracranial hypertension
Episodic
encephalopathy
Variable Variable Precipitant induced
Persistent
encephalopathy
Variable Genarally large Most often seen after portocaval
surgery or TIPS
Minimal
encephalopathy
Variable Variable Requires neuropsychological/
neurophysiological testing
TIPS, transjugular intrahepatic portosystemic shunt.
Table 1. Classification of hepatic encephalopathy.
Miscellanea on Encephalopathies – A Second Look
2
Minimal hepatic encephalopathy (MHE), the mildest form of HE, is characterized by subtle
motor and cognitive deficits, and impairs health-related quality of life (HRQOL).
2
Cirrhotic patients with MHE have a normal neurological and mental status by the standards
of clinical examination, yet demonstrate quantifiable neuropsychological defects.
3
The term
MHE refers to the subtle changes in cognitive function, electrophysiological parameters,
cerebral neurochemical/neurotransmitter homeostasis, cerebral blood flow, metabolism,
and fluid homeostasis that can be observed in patients with cirrhosis who have no clinical
evidence of hepatic encephalopathy.
4
MHE has been described previously using several different names, such as, early, low-
grade, latent or subclinical HE to identify patients with subtle cognitive function
abnormalities.
These subtle neurocognitive abnormalities primarily affect attention, speed of information
processing, and motor abilities and coordination that are not recognizable on standard
neurological examination. These neurocognitive abnormalities are independent of sleep
dysfunction or problems with overall intelligence.
5-8
It has been well-described that MHE has a subtle but negative impact on a patient’s spatial
skills, motor skills, the ability to perform complex tasks such as driving, and even quality of
life.
3-5
MHE predicts the development of overt HE and is associated with poor survival
2
. Its
negative impact on daily living, among other reasons, has led some authors to suggest that
the failure to diagnose this condition could be classified as a medical error.
9,10
2. Epidemiology
There are no accurate data on the incidence of HE. HE is classified as: overt hepatic
encephalopathy (OHE) and MHE.
OHE occurs in 30% to 45% of cirrhotic patients
11
and in 10% to 50% of patients with TIPS
12
and can be clinically diagnosed.
The true prevalence of MHE in patients with portal hypertension is inknown. MHE has been
diagnosed in patients with liver cirrhosis and in patients with noncirrhotic portal
hypertension. The prevalence of MHE has been reported in as many as 20%−84% of
cirrhotics, depending on which methods or tools are used and fixed diagnostic cut-offs.
2,3
Large variations in the prevalence of MHE are related to prior episode of OHE, severity of
liver disease, age, preasence of esophageal varices, and surgical porto-systemic shunts.
Patients who develop MHE are older, more often have alcohol as etiology of cirrhosis, have
history of overt HE in the past, have more severe liver disease, and more often have
esophagogastric varices.
2,13
3. Pathogenesis
Despite much scientific research, the exact pathophysiological mechanisms leading to HE
are not clearly understood. The most widely accepted theory of the pathogenesis of HE is
that nitrogenous substances derived from the gut adversely affect the cerebral function.
Minimal Hepatic Encephalopathy (MHE)
3
3.1 Ammonia
There are various explanations why liver dysfunction or portosystemic shunting might lead
to encephalopathy. In healthy subjects, intestinal neurotoxins, such as ammonia, manganase
and the benzodiazepine-GABA system generated by gut bacteria from food, are transported
by the portal vein to the liver, where 80–90% is metabolized and/or excreted immediately.
In all subtypes of hepatic encephalopathy this process is impaired, either because
the hepatocytes are incapable of metabolizing the neurotoxins or because portal venous
blood bypasses the liver through collateral circulation or a medically constructed shunt.
Neurotoxins accumulate in the systemic circulation. Ammonia plays a key role in the
pathogenesis of HE. The small molecules of ammonia cross the blood-brain barrier and are
absorbed and metabolized by astrocytes, population of cells in the brain that constitutes 30%
of the cerebral cortex. Alzheimer type II astrocytes are the only cells containing glutamine
synthetase that metabolize ammonia. It is hypothesed that glutamine synthesis within the
astrocytes causes brain swelling.
14,15
Astrocytes also provide physical and nutritional
support for neurons, maintain the integrity of the blood–brain barrier and regulate cerebral
blood flow.
16
Ammonia also modulates glutamate neurotransmission and induces
neurosteroid production in neurons, leading to a positive modulatory effect on the gamma-
aminobutyric acid-A receptor.
17
The precise molecular mechanism(s) responsible for
neurological alteration in HE are not known. HE is associated with alterations in the
expression of astrocytic and neuronal genes that code for various proteins that play a critical
role in central nervous system function including maintenance of cell volume and
neurotransmission.
14
The pathogenesis of MHE is similar to that of HE.
18-22
An increase in brain glutamine and
brain water is pathophysiological change associated with deterioration in
neuropsychological performance. Alterations in cerebral blood flow and glucose metabolism
induced by ammonia are associated with a significant decrease of glucose utilization by
various cortical regions that are involved in cognitive functions.
21
The cerebral metabolic
rate for ammonia and the permeability-surface area product for ammonia are significantly
higher in patients with MHE.
21
The increased permeability-surface area product of the
blood–brain barrier permits ammonia to diffuse across the blood–brain barrier into the brain
more freely than normal. This may cause ammonia-induced encephalopathy even though
arterial ammonia levels are normal or near normal.
Cognitive deficits observed in patients with noncirrhotic portal hypertension have also been
linked to ammonia.
18
Patients with noncirrhotic portal hypertension, such as extrahepatic
portal venous obstruction, exhibited abnormalities in the results of neuropsychological tests,
oral glutamine challenge test, and magnetic resonance (MR) imaging and spectroscopy
similar to those described in HE associated with cirrhosis.
22
Other waste products implicated in hepatic encephalopathy include mercaptans (substances
containing a thiol group), short-chain fatty acids and phenol.23
3.2 Serotonin
Serotonin, a neurotransmitter with widespread distribution in the CNS, is important for the
regulation of sleep, circadian rhythmicity and locomotion. Changes in the synthesis,
metabolism, storage and release of neuronal serotonin in HE suggest a serotonergic synaptic
[...]... 2007;25:1 1–1 6 18 Miscellanea on Encephalopathies – A Second Look [8] Kharbanda PS, Saraswat VA, Dhiman RK Minimal hepatic encephalopathy: diagnosis by neurophchological and neurophysiological methods Indian J Gastroenterol 2003; 22: 53 7–5 41 [9] Ortiz M, Jacas C, Cordoba J Minimal hepatic encephalopathy: diagnosis, clinical signifi cance and recommendations J Hepatol 2005;42: 4 5–5 3 [10] Lockwood AH “What’s...4 Miscellanea on Encephalopathies – A Second Look deficit Serotonin metabolism is exquisitely and selectively sensitive to the degree of portosystemic shunting and hyperammonaemia, suggesting a role for serotonin in early neuropsychiatric symptoms of HE.24 3.3 Branched-chain amino acids (BCAA) and false neurotransmitters An imbalans between aromatic aminoacids (AAA) (phenylalanine, tryptophan and... frontal rhythmic theta activity and paroxysmal, bilateral, high voltage delta waves are also frequent Sometimes bilateral spike-waves complexes or triphasic waves in the frontal regions are found (Fig 1) Convulsions are often a late stage manifestation of chronic renal failure Seizures are usually generalized tonic-clonic convulsions Nevertheless, focal motor seizures are not uncommon Epilepsia partialis... battery examines many of the abnormalities seen in patients with MHE, including motor speed and accuracy, visuo-spatial orientation, visual perception, visual construction, attention, concentration, and, to a lesser extent, memory PHES has a prognostic value for the occurrence of overt HE and mortality in cirrhotic patients.74,75 12 Miscellanea on Encephalopathies – A Second Look The RBANS contains measures... tryptophan and tyrosine) and branched-chain amino acids (BCAA)(leucine, isoleucine and valine) has been described in patients with severe liver dysfunction AAA and BCAA share a common transport mechanism into the CNS AS a consequence of increased concentration of AAA, neuronal levels may be raised leading to the production of false neurotransmitters (octopamide and phenylethanolamide)25 with subsequent... minimal hepatic encephalopathy Hepatology 2008; 47: 59 6–6 04 [53] Venktaramarao SH, Mittal, Prabhakar S, Dhiman RK Brain perfusion single photon emission computed tomography (SPECT) abnormalities in patients with minimal hepatic encephalopathy (abstract) J Gastroenterol Hepatol 2008; 23 : A6 2 [54] Grover VP, Dresner MA, Forton DM, et al Current and future applications of magnetic resonance imaging and... spectroscopy alterations and cerebral ammonia and glucose metabolism in cirrhotic patients with and without hepatic encephalopathy Gut 2007; 56: 173 6–4 2 [96] Lodi R, Tonon C, Stracciari A et al Diffusion MRI shows increased water apparent diffusion coefficient in the brains of cirrhotics Neurology 2004; 62: 76 2–6 [97] Kale RA, Gupta RK, Saraswat VA et al Demonstration of interstitial cerebral edema with... the patients 4 Clinical characteristics OHE is traditionally classified into four grades according to the West Haven criteria (Table 2).6 Grade 0 Grade 1 Grade 2 Grade 3 Grade 4 Lack of detectable changes in personality or behavior No asterixis Trivial lack of awareness Euphoria or anxiety Shortened attention span Impaired performance of addition Asterixis may be present Lethargy or apathy Minimal disorientation... 62 2–3 0 20 Miscellanea on Encephalopathies – A Second Look [46] Watanabe A, Tuchida T, Yata Y, Kuwabara Y Evaluation of neuropsychological function in patients with liver cirrhosis with special reference to their driving ability Metab Brain Dis 1995;10: 23 9–4 8 [47] Wein C, Koch H, Popp B, Oehler G, Schauder P Minimal hepatic encephalopathy impairs fitness to drive Hepatology 2004; 39:73 9–4 5 [48] Marotolli... compared with healthy controls Affects an estimated 60% (50% to 80%)* of patients with cirrhosis Cerebral dysfunction has a major impact on patients’ daily living The presence of a disease that can cause MHE, such as, cirrhosis and/or the presence of a portalsystemic shunt normal mental status on clinical examination demonstration of abnormalities of cognition and/or neurophysiological variables . MISCELLANEA ON ENCEPHALOPATHIES – A SECOND LOOK Edited by Radu Tanasescu MISCELLANEA ON ENCEPHALOPATHIES – A SECOND LOOK Edited by Radu Tanasescu Miscellanea. Encephalopathy 327 Radu Tanasescu, Laura Dumitrescu, Carmen Dragos, Dimela Luca, Alexandra Oprisan, Catalina Coclitu, Oana Simionescu, Lorena Cojocaru, Marius Stan, Andreea Carasca, Andreea Gitman,. dysfunction. AAA and BCAA share a common transport mechanism into the CNS. AS a consequence of increased concentration of AAA, neuronal levels may be raised leading to the production of false neurotransmitters
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